SEISMIC RETROFITTING OF EARTHQUAKE-DAMAGED CONCRETE COLUMNS BY LATERAL PRE-TENSIONING OF FRP BELTS
SEISMIC RETROFITTING OF EARTHQUAKE-DAMAGED CONCRETE COLUMNS BY LATERAL PRE-TENSIONING OF FRP BELTS
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发表时间：
2006
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影响因子：
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通讯作者：
K. N. Nesheli;K. Meguro
中科院分区：
文献类型：
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作者：
K. N. Nesheli;K. Meguro
构造了5根剪跨高比分别为1.5和2.5的方柱，模拟半缩尺剪损柱，并进行了恒轴压和反复水平荷载作用下的试验。试验后，两个不同剪跨比的柱在裂缝模式和侧向承载力下降方面受到一定程度的损伤。然后，这些地震损坏的柱进行了加固预张拉碳或芳纶纤维增强塑料带，并再次进行了循环水平荷载和恒定轴压下的测试。由于约束装置，即FRP带，在向柱施加横向荷载之前被预张紧，因此使用了主动和被动约束。由于预应力的作用，受损柱的初始裂缝立即闭合。值得一提的是，这项加建工程无须采取任何修补措施，例如清除受损的混凝土或注入裂缝等，因此速度非常快。此外，预应力技术是一种创新的方法，可以用简单的扳手手动施加。试验结果表明，原柱的抗侧承载力突然下降，表现为脆性剪切破坏。当受损柱通过预张拉FRP带进行加固时，侧向强度可以恢复，并且可以防止抗剪承载力的下降，直到大的偏移，表明更好的抗震性能。
Five square columns with two shear span-to-depth ratios of 1.5 and 2.5 were constructed to model half-scale shear-deficient columns and tested under constant axial compression and reversed cyclic lateral load, simultaneously. After being tested, two of the columns with different shear span-to-depth ratios were subjected to a certain level of damage in terms of crack pattern and also drop in the lateral capacity. Then, these earthquake-damaged columns were retrofitted by pre-tensioned carbon or aramid FRP belts, and once more, were tested under cyclic lateral loading and constant axial compression. As the confining devices, i.e. FRP belts, were pre-tensioned before applying the lateral load to the columns, both active and passive confinements were utilized. As an instant result of pretensioning, the initial cracks of the damaged column were closed. It should be noted that this retrofitting procedure is quick as it is carried out without any repair measures such as removal of damaged concrete or crack injection and so on. Moreover, the prestressing technique is an innovative method and can be applied manually using a simple wrench. According to test results, the lateral capacity of the original columns dropped suddenly, showing a brittle shear failure. When the damaged columns were retrofitted by pre-tensioned FRP belts, the lateral strength could be restored and the drop in shear capacity could be prevented up to large drifts, indicating a better seismic performance.